1. Field of the Invention
The invention relates to a method for manufacturing a load-bearing member, and more particularly to a method and a system for manufacturing a nested profile combination.
2. Description of the Related Art
As shown in FIGS. 6-9, a typical nested profile combination includes a first profile member 1′ and a second profile member 2′. The first profile member 1′ and the second profile member 2′ are strip members having cross sections of the same shapes and sizes. The nesting process includes: rotating the first profile member 1′ for 180°, and nesting the first profile member 1′ and the second profile member 2′. A cross section of the first profile member 1′ includes: two first transverse sides 11′, a first lateral side 12′, a first embedded flanging 13′, a first encircling flanging 14′, a first bent part 131′, and a first stiffener 121′. The two first transverse sides 11′ are arranged in parallel. Two ends of the first lateral side 12′ are perpendicularly connected to one end of each of the first transverse sides 11′, respectively. The first embedded flanging 13′ and the first encircling flanging 14′ are oppositely arranged on the other end of each of the first transverse sides 11′, respectively. The first bent part 131′ is formed by bending an end of the first embedded flanging 13′ inwards. The first lateral side 12′ is concaved inwardly to form the first stiffener 121′. A cross section of the second profile member 2′ includes: two second transverse sides 21′, a second lateral side 22′, a second embedded flanging 23′, a second encircling flanging 24′, a second bent part 231′, and a second stiffener 221′. The two second transverse sides 21′ are arranged in parallel. Two ends of the second lateral side 22′ are perpendicularly connected to one end of each of the second transverse sides 21′, respectively. The second embedded flanging 23′ and the second encircling flanging 24′ are oppositely arranged on the other end of each of the second transverse sides 21′, respectively. The second bent part 231′ is formed by bending an end of the second embedded flanging 23′ inwards. The second lateral side 22′ is concaved inwardly to form the second stiffener 221′. In assembly of the first and the second profile members, allow the first transverse sides 11′ to contact with the second transverse sides 21′, the first embedded flanging 13′ to contact with an inner surface of the second lateral side 22′, the first encircling flanging 14′ to contact with an outer surface of the second lateral side 22′, and the first bent part 131′ to contact with a second inwardly convex part 222′ of the second stiffener 221′. Allow the second embedded flanging 23′ to contact with an inner surface first lateral side 12′, the second encircling flanging 24′ to contact with an outer surface of the first lateral side 12′, the second bent part 231′ to contact with a first inwardly convex part 122′ of the first stiffener 121′. When the first profile member 1′ and the second profile member 2′ are nested, an end of the first encircling flanging 14′ is bent inwardly to form a first undercut 141′; an end of the second encircling flanging 24′ is bent inwardly to form a second undercut 241′. Thus, the first undercut 141′ is attached to a second outwardly concaved part 223′ of the second stiffener 221′; and the second undercut 241′ is attached to a first outwardly concaved part 123′ of the first stiffener 121′, thereby realizing the position limitation of the first profile member 1′ and the second profile member 2′ in a direction along lateral side. To intensify the intensity and rigidity of the profile, the first stiffener 121′ is provided with a first recess 124′ having a C-shaped cross section, and an opening of the first recess 124′ faces the same direction of an opening of the first profile member 1′. The second stiffener 221′ is provided with a second recess 224′ having the C-shaped cross section, and an opening of the second recess 224′ faces the same direction of an opening of the second profile member 2′. The first transverse sides 11′ are provided with first convex ribs 111′, respectively; and the second transverse sides 21′ are provided with the second convex ribs 211′.
A typical method for manufacturing the nested profile combination includes: manufacturing two separate profile members, and performing cutting, perforating (multi-station), and stiffener formation on the profile members; rolling the profile members to form the transverse sides, the lateral sides, the embedded flangings, and the encircling flangings; nesting the two profile members together; and bending the encircling flangings inwardly by rolling to fastening corresponding lateral sides.
The above method is performed on different stations off-line, thereby resulting in discrete processes and transfer between different stations. The method is disadvantageous in the following aspects: first, the method has a large consumption of energy and time, as well as poor manufacture precision and large positioning error. For example, as the perforating process is followed by stiffener formation process, the precision of the distance between through holes is influenced by the stretching and deformation of the profile in the stiffener formation. Furthermore, procedures of multi-station necessitate auxiliary procedures for adjustment and clamping, which consume much auxiliary work time and result in accumulated error in different procedures. Finally, the machining, cutting, perforating, and rolling processes require manual feed of the material, which not only has low speed and efficiency, but also is difficult to control the geometric precision and form and position tolerance, thereby resulting in low material utilization and low yield.